1. Field of the Invention
The present invention concerns a liquid propellant supply device intended for a satellite and applies in particular to commercial geostationary satellites.
2. Description of the Prior Art
Whatever propulsion system is used for stationkeeping and attitude control of a geostationary satellite, the satellite is no longer usable once the propellant(s) stored in the storage tank(s) of the supply device is/are exhausted.
Numerous devices have been designed to indicate with greater or lesser accuracy: either the remaining volume of propellants in the storage tank(s) at a given time or the time at which the storage tank(s) become empty.
The first category includes all zero or very low gravity volumetric measurement devices and the second includes all devices for detecting gas bubbles at the outlet from the storage tanks.
A third category of end of service life detector devices combines a device from the first or more usually the second category and one or more small additional storage tanks which are just sufficient to remove the satellite from orbit, the additional storage tank(s) being disposed in parallel or in series with the main storage tank(s).
The disadvantages of devices from the first category relate to their complexity, resulting from the need for accuracy, and the disadvantages of devices from the second and third categories relate to the need to detect the very first bubble.
Because the date at which the mission of the satellite ends cannot be predicted before it actually comes about, it is not then possible to implement any measures to continue the mission, for example, to reoptimize a satellite telecommunication network.
An object of the invention is to alleviate the disadvantages associated with these prior art solutions and to enable easy and reliable detection of the approach of complete exhaustion of at least one propellant of the satellite at a time when there remains a predetermined quantity of that propellant.